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For developing the applications of integrated optics to microwave and millimeter wave systems, a key point is the very high speed modulation of the lightwave. As external modulations seem to constitute the best solution, they need the availability of specific driving devices. The main requirements of these devices are given, in terms of speed (current gain cut-off frequency), current density, and breakdown voltage. The principle and capabilities of various kinds of field effects transistors available are summarized, with a large insistance on those that present the greatest potential such as the High Electron Mobility Transistors (HEMT) on InP substrate. Finally, the recent improvement of performance (speed, current density, breakdown voltage) are presented and discussed. It appears that the requirement on breakdown voltage remains the most difficult to satisfy for very high speed devices such as HEMT on InP but recent results lets hope the availability of satisfying devices in near future.

p‐type alloyed ohmic contacts of Au/Mn/Ni/Au have been fabricated for application to compound semiconductor devices. Extremely low resistance contacts to 3×1019 cm−3 Be‐doped p‐GaAs were achieved by electron‐beam evaporation and rapid thermal annealing. Contacts were thermally stable, and the contact resistance remained below 0.04 Ω mm in the temperature range from 360 to 450 °C. Annealing at 400 °C for 40 s resulted in a minimum contact resistance of 0.012 Ω mm, corresponding to a specific resistivity of 1.6×10−8 Ω cm2, which is very close to the theoretical predictions. The mechanism of formation of Au/Mn ohmic contacts was discussed, based on Auger electron spectroscopy data.

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